The present invention is directed to a heat-shrinkable envelope or sleeve comprising at least one heat-shrinkable component and of a mechanical reinforcement component.
British patent application No. 1,497,051, which was the basis of the German Gebrauchsmuster No. 75 01 913, discloses a heat-shrinkable envelope or sleeve having a reinforcing insert for reinforcing the mechanical properties of the sleeve. Here, however, only the longitudinally directed reinforcing elements are used so that the shrink direction of the envelope is not influenced. The result of this, however, is that injuries, such as, for example, tears in a longitudinal direction, can continue unimpeded. This is especially dangerous when these injuries occur adjacent a face edge prior to the heat-shrinking operation, since a further tearing in the longitudinal direction of the envelope cannot be stopped during the shrinking operation as a consequence of the shrinking forces.
In order to solve this problem, for example, weaves or fabrics have also been inserted as reinforcing elements, as disclosed in European patent application No. 0,117,026. In this arrangement, shrinkable weaves are used and are embedded in a non-shrinkable material. In order to achieve a correspondingly higher, mechanical strength, non-shrinkable, heat-resistant, non-metallic threads that proceed in a second fabric direction, are also introduced into these fabrics in addition to the shrinkable threads proceeding in the first shrinkable direction. Thus, the heat-shrinkable component is woven in a matrix with the non-shrinkable component. Since the second direction is defined by the shrinkable components, the inserts of the present invention provide production essentially only against injuries in only one direction. On the other hand, the manufacture of envelopes having such weaves with different components is extremely involved and may also be complicated under certain conditions due to the differently constituted materials. Since the individual components are composed of natural or synthetic, electrically non-conductive materials, for example, electrically as well as magnetic shielding cannot be achieved with such a weave or reinforcing element.